A clause that tells how, when, where, or to what extent something was done is called an adverb or adverbial clause. An adverb clause consists of words that has a subject and a verb, but functions as an adverb. It modifies an adjective, verb and an adverb. For example: Although she has a medical degree, she is working as a business woman. The adverb clause in this sentence is, "although she has a medical degree".
